Despite health-related harms, individuals continue to use cannabis and tobacco. A major barrier to successful cessation is the experience of withdrawal. Tobacco withdrawal has been well documented (102). The next iteration of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) is considering the inclusion of cannabis withdrawal as a criterion in the diagnosis of cannabis use disorders (103;104). Based on multiple clinical (105;106) and epidemiological (107;108) studies, little doubt remains in the reliability and validity of the cannabis withdrawal syndrome. However, as a majority of cannabis users also smoke tobacco, it is necessary to examine both unique and shared components of the withdrawal syndrome that emerge consequent to cessation of one or both drugs. Cannabis withdrawal is characterized by anger, aggression or irritability, nervousness or anxiety, sleep difficulties, decreased appetite or weight loss, psychomotor agitation or restlessness, depressed mood, and less commonly by physical symptoms such as stomach pain or shakes/tremors (109). Many of these withdrawal features are also noted subsequent to tobacco cessation, which has led to direct comparisons of these withdrawal syndromes (110-112). While the number of
